228 ALLEN'S NATURALIST'S LIBRARY. 



limbs being shorter, however, than the fore-, and the thumb of 

 the fore-limb is sometimes very rudimentary, being only a nail- 

 less tubercle or, in the majority of the species, entirely absent, 

 rendering the hand a much less perfect organ for holding or 

 picking up small objects, such as fruits, &c. ; but its absence 

 probably does not affect, if it does not even benefit, the hand 

 as an organ for climbing and catching hold again after a long 

 leap. The nails and other digits of both limbs are compressed, 

 but much less so than in Brachyteles and Lagothrix. The tail is 

 very long, generally exceeding the length of the body and head, 

 and is nude on the under side, and very sensitive towards its 

 termination. As a prehensile organ it has reached the summit 

 of strength and perfection. " It even serves as a fifth hand, as 

 detached objects, otherwise out of reach, can be grasped by 

 it, and brought towards the hand or mouth." (Mivart.} The 

 body is covered with long, rather coarse, generally black, hair, 

 and has no woolly under-fur, as in Lagothriic and Brachyteles. 

 With regard to the skeleton of Ateles, the lumbar region of the 

 vertebral column is short, and the dorsal segment attains agreatei 

 relative length than in any other Ape, being over nine-twentieths 

 of the total length of the spine, without the tail. (Mivart.) The 

 dorsal and lumbar vertebrae together number eighteen. In the 

 tail there are twenty-three vertebrae, flattened on the under side, 

 and exceptionally provided with bony processes, serving as 

 points for the attachment of muscles for rendering it as efficient 

 a prehensile organ as possible. The length of the whole arm and 

 hand in Ateles, in proportion to that of the spine, is 174 to 

 100 ; but without the hand it is shorter than the spine, the hand 

 itself being only slightly shorter than the latter. The propor- 

 tion of the hind-limb to the spine is somewhat less, being 169 

 to 100. The thumb is reduced to a single metacarpal bone, to 



